The present invention relates to a method for recording track marking information on flexible magnetical information carrier discs and to an apparatus for fine adjustment of the position of a reading head.
The method and apparatus according to the invention is generally applicable in mini-floppy and micro-floppy information recording systems, or in casette-systems with flexible magnetical discs, in which the eccentricity of the concentrical recording tracks is smaller than the permissible track adjusting error. The present invention facilitates the adjustment of the reading head to the information carrying tracks.
In the field of floppy technique the positioning and retrieval of circular information recording tracks is solved in such a way that concentrical and circular guiding tracks are recorded on the rear side of the circular information recording disc with an appropriate track density, e.g. 500 tracks per inch. The information recording occurs in the first side of the disc during the reading of the corresponding rear guiding tracks, and a suitable servo-mechanical system controls the position of the reading-writing head in accordance with the guiding track. The guiding tracks are used in the same way when information is read out from the disc.
In this conventional head-adjusting system a first disadvantage lies in that a complete side of the disc is not used for recording useful information but only for track-guiding. A further drawback lies in that simultaneously at both sides of the disc respective writing-reading heads should be moved. The two heads are separated by the rotating disc lying therebetween, and a precisely adjustable mechanical link must be provided between the heads which must keep the relative position of the heads unchanged during adjustments.
Such a double-sided access to the disc and the simultaneous precise adjustment of the heads raises increased difficulties in case of magnetical information recording discs placed in respective casette casings because the presence of the closed casette renders the double-sided disc access to be difficult. Apart from a number of advantages such information recording magnetical casette disc systems have not gained wide acceptance, mostly due to the problems connected with track guiding.
It is an apparent advantage of the aforesaid conventional systems using guiding tracks that its track control can compensate the accuracy errors originating from the eccentricity of the circular tracks and from the thermal deformation of the disc.